Del. $\partial, \delta, \nabla $: Correct enunciation

For what it's worth, in the community I hang out with, we generally just say "partial ecks" for $\partial_x$, and when we are feeling even lazier and when the context is clear, we call the same operator "dee-dee ecks", as if it were the ordinary $\frac{d}{dx}$.

$\nabla$, however, is always "nabla", unless it is used for the gradient of a function, in which case we say "gradient of eff" for $\vec{\nabla} f$.

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In class, however, if the expression is embedded in prose (say as part of a theorem statement), I would never read the symbol. I would instead say what it means. So while I may write

Important, we always have $\partial_x\partial_y f = \partial_y\partial_x f$

I would say,

Important, we always have that partial derivatives commute.

Or if I write

Therefore $\partial_x f = 0$

I would say

Therefore the partial derivative of eff with respect to ecks is zero.

Or if I write

By the Maxwell's equations, $\nabla\cdot E = 0$

I would say

By the Maxwell's equation, ee is divergence free.

The only time I might read the symbols as symbols is if I am performing a computation on the board and am just copying stuff directly from my notes. In those cases I honestly cannot remember what I would usually say.

Alright, I've sort of realized that there is no correct answer to this question. I'm summing up my thoughts and what I've gleaned from the other answers in this CW answer so that I can accept it.

It really depends upon context. Usually you won't see $\partial$ used with $\nabla$ together in an ambiguous manner. Usually $\partial$ will be in the form of $\frac{\partial}{\partial x}$, so it won't be confused if read out "del by del x". $\delta$ is never called del. Covariant derivatives can have their bases declared beforehand. So, here is the list of ways of pronouncing stuff:

• $\partial$ :
  • Usually: It seems to be generally read as "partial derivative of ... wrt ..." or something similar.
  • Other pronunciations: Can be also read "del", "dou", "die", "derronde", and lots of other things.
  • I guess in unambiguous situations the much faster "del by del x" can be used.
  • If reading out $\partial_x f$, read it out the long way.
• $\nabla$ :
  • Usually: When you hear "del", it's probably this fellow.
  • Other pronunciations: Also can be read out as "nabla" ("nabla dot"/"nabla cross" &c). One can use "div"/"grad"/"curl"/"covariant derivative of" to be specific.
• $\delta$ : This poor fellow is hardly used. I guess it's called del because it looks like $\partial$ and/or is a "shortened" version of $\Delta$--"DELta".
  • Usually: Just read it out as "delta" or "small delta".
  • Other pronunciations: None. Hopefully.

I personally read $\nabla$ as "nabla", and keep the rest as "del". While reading, it's OK to think of all of these as del I guess.

I don't know how relevant this is, but in Brazil, none of those symbols is called "del." $\nabla$ is Nabla, $\delta$ is (lowercase) Delta, and $\partial$ is "Derronde." (A bastardizazion of the French for "round D.")